Tubular lamp fittings

ABSTRACT

A lighting fitting to accommodate tubular electric filament lamps of alternative lengths. The lamp holders are mounted at the end of inwardly biased telescopic arms. The holders comprise a socket in which is mounted a resilient contact which is less stiff than the inward bias of the holders so that the different lengths of end caps of different tubular lamps are completely covered by the sockets. The arms are biased by means of electrically conducting springs which connect the contacts in the holders to terminals.

United States Patent [191 Beuttell [451 Feb. 12, 1974 TUBULAR LAMP FITTINGS [75] Inventor: Victor Frederick Beuttell,

Malmesbury, England [73] Assignee: Linolite Limited, Wiltshire, England 22 Filed: Sept. 13, 1971 [21] Appl. No.2 179,654

[30] Foreign Application Priority Data Sept. 22, [970 Great Britain 45,096/70 [52] US. Cl. 240/51.ll R, 240/52 R [51] Int. Cl. H051) 33/02 [58] Field of Search... 240/5l.ll R; 339/52 R, 52 S [56] References Cited UNITED STATES PATENTS Stiffel 240/51.1l R

3,060,310 10/1962 Bertsche, Jr. et al. 240/5l.ll R

Primary Examiner--Samuel S. Matthews Assistant Examiner-Russell E. Adams, Jr. Attorney, Agent, or Firm-Edwin E. Greigg ABSTRACT A lighting fitting to accommodate tubular electric filament lamps of alternative lengths. The lamp holders are mounted at the end of inwardly biased telescopic arms. The holders comprise a socket in which is mounted a resilient contact which is less stiff than the inward bias of the holders so that the different lengths of end caps of different tubular lamps are completely covered by the sockets. The arms are biased by means of electrically conducting springs which connect the contacts in the holders to terminals.

4 Claims, 4 Drawing Figures TUBULAR LAMP FITTINGS This invention relates to lighting fittings for tubular filament lamps of the type having, at both ends, an end cap via a contact of each of which electrical connection can be made with the filament.

A problem exists in relation to the manufacture of fittings for such lamps in that British standard dimensions for the lamps do not correspond exactly with other standards. For example the most widely used British lamp (284 mm in length) is shorter than most widely used Continental lamp (309 mm in length); the diameters of the tube and of the end caps of the British lamp are. smaller than that of the Continental lamp; and the length of the end caps of the British lamp is less than that of the Continental lamp. In the past this has led to the manufacture of special lighting fittings for the British market and special fittingsfor the Continental market, each so dimensioned as to receive the respective standard lamp tube.

A lighting fitting for tubular electric filament lamps in accordance with the invention has two opposed lamp holders, each for receiving an end cap of a lamp tube, one at least of which holders is movable towards and away from the other by an amount sufficient to allow at least two standard tubular filament lamps of different lengths to be alternatively fitted and is resiliently biased towards the other. Lamps of various lengths may thus be received by the holders. The movable holder or holders also facilitate removal and replacement of a lamp tube in the fitting.

} It is desirable, aesthetically and for safety, for the lamp holder completely to cover the end caps of the lamp (which are usually brass). In order to enable the holders to receive end caps of different lengths,each may comprise a cylindrical socket for receiving an end cap in which socket an electrical contact for engagement with the lamp tube contact is mounted for movement in an axial direction the contact being resiliently biased outwardly and less stiffly biased than is the holder itself. The arrangement has the effect that when a lamp is inserted in the fitting the bias of the or both holders urges them together until they abut the tubular glass envelope (which is always of larger diameter than the end caps). Theend caps are thus completely covered by the lamp holders.

. In order to allow lamp tubes of different end cap diameters to be used thelamp holders sockets are made sufficiently large to receive the largest end cap of those lamps which it is desired should fit the fitting. The mouth of each socket is preferably internally bevelled (or counter-sunk) so as to facilitate axial alignment of the lamp tube in the sockets. The bevelled surface engages'the end of the glass envelope of the lamp tube and serves to centralise the tube.

In the preferred embodiment of the invention both lamp holders aremovable and are biased towards each other by respective springs which also provide the necessary electrical connections with the lamp holder contact which comprises a resilient conducting strip, and end portion of which engages a lamp contact.

One embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: i

FIG. I is a part sectional side elevation of a lighting fitting in accordance with the invention;

FIG. 2 is a plan view of the lighting fitting shown in FIG. 1;

FIG. 3 is a side elevation of the lighting fitting shown in FIG. 1 having fitted therein a British standard tubular lamp; and

FIG. 4 is a side elevation of the lighting fitting shown in FIG. 1 having fitted therein a Continental standard lamp.

Referring particularly to FIGS. 1 and 2 it will be seen that the lighting fitting has a base comprising a mounting box 2 and a hollow square section tube 4 mounted diametrically on the box 2. Twoplastics' lamp holders 6 each have square section arms 8 which are telescopically mounted in opposite ends of the tube 4. The lamp holders provide opposed sockets ll0 each for receiving an end capofa tubular lamp when fitted in the lighting fitting. i

A holder-contact 12 comprises :a flexible conducting strip and is mounted at one of its-ends 14 on a spigot 15 in each of the lamp holders 6 so that its opposite end 16 is aligned with the longitudinal axis of the socket 10. The contact 18 of the end cap 20 of a lamp tube 22 when inserted into the socket thus makes electrical contact with the end portion 16 of the holder-contact l2.

The end portion 14 of each holder-contactlZ is con nected by an electrically conducting tension spring 24 to a respective terminal (not shown) in an insulating terminal box 26 at the mid-point of the tube 4. We prefer to make the hollow tube 4 as an aluminium extru- .sion and in this case the straight portion 27 of the conducting tension spring is provided with an insulating sleeve of plastics material.

When a lamp tube 22 is inserted in the fitting the end portion 16 of the holder-contact 12 engages the contact 18 of the respective end cap of the lamp thus establishing contact between the contact 18 and the respective terminal in the terminal box 26.The lamp holder 6 is drawn inwardly by the spring 24 until a bevelled surface 28 at the mouth of the socket 10 engages against the shoulder 30 of the glass envelope of the lamp tube. The bevelled surfaces 28 tend to align the lamp tube axially between the sockets. To ensure this action the springs 24 are made stiffer than the resilient contacts 12. v I

The bore of the sockets 10 is sufficiently large to accommodate the end cap of a 309 mm Continental lamp tube. The end caps of the corresponding 284 mm British lamp tube being smaller also fit within the sockets. The end cap of the Continental end tube is longer than that of the British and thus depresses the portion 16 of the contact 12 to a greater extent. Also as the Continental lamp'tube is longer than the British lamp tube the lamp holders are further extended against the action of the springs 24 when a Continental lamp tube is fitted.

In FIG. 3 a British lamp tube 221; is shown in the lamp fitting. In FIG. 4 a Continental lamp tube 22c is shown in the lamp fitting. It will be noted that the diameter of the glass envelope 32c of the Continental lamp tube 22c is greater than the diameter of the glass envelope 32b of the British lamp tube 22b and that this difference in diameter is adequately allowed for by the spacing between the axes of the sockets l0 and the tube 4.

The lamps shown in the drawings may be modified for example the mounting box 2 may not be required in which case-the fitting may be screwed directly to the wall or mounted on a simple channel mounting. The lamp fitting may be in the form ofa desk lamp, in which case the tube 4 is mounted at the end of an arm extending upwardly from a base or stand. The fitting may be provided with shades and/or reflectors. For example a reflector may be mounted behind the lamp tube on the tube 4. A lamp shade may also be mounted on the tube 4 or may for example be provided with clips for mount ing directly on the lamp tube.

l'claim:

l. A lighting fixture for tubular filament lamps having a cap portion at eacn end, each said cap portion including an electrical contact which together define a longitudinal axis of the lamp, the fixture comprising:

a. a support member;

b. a pair of filament lamp holders, each one of said pair being mounted on said support member, each of said holders including an inwardly facing socket for receiving therein an end cap of a filament lamp; and

c. means enabling at least two standard tubular filament lamps of different standard lengths each of which may have end cap portions of different lengths to be alternatively fitted between the sockets of said pair of holders, said means comprising:

i. means slidably mounting at least one of said holders on said support member;

ii. resilient first means biasing said slidably mounted holder toward the other said holder;

(iii) electrical contact means mounted within eac holder and engageable with the electrical contact of an inserted cap portion; and

(iv) resilient second means biasing said contact means within said slidably mounted holder toward the lamp, said resilient first means being stiffer than said resilient second means.

2. A lighting fixture as defined in claim 1, wherein the open end of each socket is provided with a bevelled surface which serves to axially locate the filament lamp by engagement with its glass envelope.

3. A lighting fixture as defined in claim 1, wherein both said lamp holders are slidably mounted and biased towards each other by said resilient first means, said resilient first means providing an electrical connection with said electrical contact means.

4. A lighting fixture as defined in claim 1, wherein said slidable mounting means comprises telescopic arm arranged to telescopically engage said support member. 

1. A lighting fixture for tubular filament lamps having a cap portion at eacn end, each said cap portion including an electrical contact which together define a longitudinal axis of the lamp, the fixture comprising: a. a support member; b. a pair of filament lamp holders, each one of said pair being mounted on said support member, each of said holders including an inwardly facing socket for receiving therein an end cap of a filament lamp; and c. means enabling at least two standard tubular filament lamps of different standard lengths each of which may have end cap portions of different lengths to be alternatively fitted between the sockets of said pair of holders, said means comprising: i. means slidably mounting at least one of said holders on said support member; ii. resilient first means biasing said slidably mounted holder toward the other said holder; (iii) electrical contact means mounted within each holder and engageable with the electrical contact of an inserted cap portion; and (iv) resilient second means biasing said contact means within said slidably mounted holder toward the lamp, said resilient first means being stiffer than said resilient second means.
 2. A lighting fixture as defined in claim 1, wherein the open end of each socket is provided with a bevelled surface which serves to axially locate the filament lamp by engagement with its glass envelope.
 3. A lighting fixture as defined in claim 1, wherein both said lamp holders are slidably mounted and biased towards each other by said resilient first means, said resilient first means providing an electrical connection with said electrical contact means.
 4. A lighting fixture as defined in claim 1, wherein said slidable mounting means comprises telescopic arm arranged to telescopically engage said support member. 